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242 lines
8.4 KiB
C
242 lines
8.4 KiB
C
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/*============================================================================
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This C source fragment is part of the Berkeley SoftFloat IEEE Floating-Point
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Arithmetic Package, Release 2c, by John R. Hauser.
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THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort has
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been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT TIMES
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RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO PERSONS
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AND ORGANIZATIONS WHO CAN AND WILL TOLERATE ALL LOSSES, COSTS, OR OTHER
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PROBLEMS THEY INCUR DUE TO THE SOFTWARE WITHOUT RECOMPENSE FROM JOHN HAUSER OR
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THE INTERNATIONAL COMPUTER SCIENCE INSTITUTE, AND WHO FURTHERMORE EFFECTIVELY
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INDEMNIFY JOHN HAUSER AND THE INTERNATIONAL COMPUTER SCIENCE INSTITUTE
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(possibly via similar legal notice) AGAINST ALL LOSSES, COSTS, OR OTHER
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PROBLEMS INCURRED BY THEIR CUSTOMERS AND CLIENTS DUE TO THE SOFTWARE, OR
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INCURRED BY ANYONE DUE TO A DERIVATIVE WORK THEY CREATE USING ANY PART OF THE
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SOFTWARE.
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Derivative works require also that (1) the source code for the derivative work
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includes prominent notice that the work is derivative, and (2) the source code
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includes prominent notice of these three paragraphs for those parts of this
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code that are retained.
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=============================================================================*/
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/*----------------------------------------------------------------------------
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| Underflow tininess-detection mode, statically initialized to default value.
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| (The declaration in `softfloat.h' must match the `int8' type here.)
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*----------------------------------------------------------------------------*/
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int8 float_detect_tininess = float_tininess_after_rounding;
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/*----------------------------------------------------------------------------
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| Raises the exceptions specified by `flags'. Floating-point traps can be
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| defined here if desired. It is currently not possible for such a trap
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| to substitute a result value. If traps are not implemented, this routine
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| should be simply `float_exception_flags |= flags;'.
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*----------------------------------------------------------------------------*/
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void float_raise( int8 flags )
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{
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float_exception_flags |= flags;
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}
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/*----------------------------------------------------------------------------
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| Internal canonical NaN format.
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*----------------------------------------------------------------------------*/
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typedef struct {
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flag sign;
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bits32 high, low;
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} commonNaNT;
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/*----------------------------------------------------------------------------
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| The pattern for a default generated single-precision NaN.
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*----------------------------------------------------------------------------*/
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enum {
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float32_default_nan = 0xFFFFFFFF
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};
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/*----------------------------------------------------------------------------
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| Returns 1 if the single-precision floating-point value `a' is a NaN;
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| otherwise returns 0.
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*----------------------------------------------------------------------------*/
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flag float32_is_nan( float32 a )
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{
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return ( 0xFF000000 < (bits32) ( a<<1 ) );
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}
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/*----------------------------------------------------------------------------
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| Returns 1 if the single-precision floating-point value `a' is a signaling
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| NaN; otherwise returns 0.
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*----------------------------------------------------------------------------*/
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flag float32_is_signaling_nan( float32 a )
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{
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return ( ( ( a>>22 ) & 0x1FF ) == 0x1FE ) && ( a & 0x003FFFFF );
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}
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#ifdef DOUBLES
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/*----------------------------------------------------------------------------
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| Returns the result of converting the single-precision floating-point NaN
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| `a' to the canonical NaN format. If `a' is a signaling NaN, the invalid
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| exception is raised.
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*----------------------------------------------------------------------------*/
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static commonNaNT *float32ToCommonNaN( float32 a )
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{
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static commonNaNT z;
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if ( float32_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
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z.sign = a>>31;
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z.low = 0;
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z.high = a<<9;
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return &z;
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}
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#endif
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#ifdef DOUBLES
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/*----------------------------------------------------------------------------
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| Returns the result of converting the canonical NaN `a' to the single-
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| precision floating-point format.
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*----------------------------------------------------------------------------*/
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static float32 commonNaNToFloat32( commonNaNT *a )
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{
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return ( ( (bits32) a->sign )<<31 ) | 0x7FC00000 | ( a->high>>9 );
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}
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#endif
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/*----------------------------------------------------------------------------
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| Takes two single-precision floating-point values `a' and `b', one of which
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| is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a
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| signaling NaN, the invalid exception is raised.
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*----------------------------------------------------------------------------*/
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static float32 propagateFloat32NaN( float32 a, float32 b )
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{
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flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
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aIsNaN = float32_is_nan( a );
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aIsSignalingNaN = float32_is_signaling_nan( a );
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bIsNaN = float32_is_nan( b );
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bIsSignalingNaN = float32_is_signaling_nan( b );
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a |= 0x00400000;
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b |= 0x00400000;
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if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
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if ( aIsNaN ) {
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return ( aIsSignalingNaN & bIsNaN ) ? b : a;
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}
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else {
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return b;
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}
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}
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#ifdef DOUBLES
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/*----------------------------------------------------------------------------
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| The pattern for a default generated double-precision NaN. The `high' and
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| `low' values hold the most- and least-significant bits, respectively.
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*----------------------------------------------------------------------------*/
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enum {
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float64_default_nan_high = 0xFFFFFFFF,
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float64_default_nan_low = 0xFFFFFFFF
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};
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/*----------------------------------------------------------------------------
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| Returns 1 if the double-precision floating-point value `a' is a NaN;
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| otherwise returns 0.
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*----------------------------------------------------------------------------*/
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flag float64_is_nan( float64 a )
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{
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return
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( 0xFFE00000 <= (bits32) ( a.high<<1 ) )
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&& ( a.low || ( a.high & 0x000FFFFF ) );
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}
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/*----------------------------------------------------------------------------
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| Returns 1 if the double-precision floating-point value `a' is a signaling
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| NaN; otherwise returns 0.
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*----------------------------------------------------------------------------*/
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flag float64_is_signaling_nan( float64 a )
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{
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return
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( ( ( a.high>>19 ) & 0xFFF ) == 0xFFE )
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&& ( a.low || ( a.high & 0x0007FFFF ) );
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}
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/*----------------------------------------------------------------------------
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| Returns the result of converting the double-precision floating-point NaN
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| `a' to the canonical NaN format. If `a' is a signaling NaN, the invalid
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| exception is raised.
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*----------------------------------------------------------------------------*/
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static commonNaNT float64ToCommonNaN( float64 a )
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{
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commonNaNT z;
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if ( float64_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
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z.sign = a.high>>31;
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shortShift64Left( a.high, a.low, 12, &z.high, &z.low );
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return z;
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}
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/*----------------------------------------------------------------------------
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| Returns the result of converting the canonical NaN `a' to the double-
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| precision floating-point format.
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*----------------------------------------------------------------------------*/
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static float64 commonNaNToFloat64( commonNaNT a )
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{
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float64 z;
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shift64Right( a.high, a.low, 12, &z.high, &z.low );
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z.high |= ( ( (bits32) a.sign )<<31 ) | 0x7FF80000;
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return z;
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}
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/*----------------------------------------------------------------------------
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| Takes two double-precision floating-point values `a' and `b', one of which
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| is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a
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| signaling NaN, the invalid exception is raised.
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*----------------------------------------------------------------------------*/
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static float64 propagateFloat64NaN( float64 a, float64 b )
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{
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flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
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aIsNaN = float64_is_nan( a );
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aIsSignalingNaN = float64_is_signaling_nan( a );
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bIsNaN = float64_is_nan( b );
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bIsSignalingNaN = float64_is_signaling_nan( b );
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a.high |= 0x00080000;
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b.high |= 0x00080000;
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if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
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if ( aIsNaN ) {
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return ( aIsSignalingNaN & bIsNaN ) ? b : a;
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}
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else {
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return b;
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}
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}
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#endif
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